I just ran across this article:
where Canon Europe says:
Canon has announced that it is extending its offer of a free two-year warranty for the EOS-1D Mark IV to include all cameras that are purchased before 30 June 2012.
This two-year warranty is a one-year extension on top of the standard Canon one-year European warranty that’s offered on all products, and it will be operating under identical terms and conditions. This gives photographers a total warranty period of two years from the date of purchase of their new product.
Canon is not only providing this extended two-year warranty on new EOS-1D Mark IV purchases, but it is also making it available to all existing owners of EOS-1D Mark IV bodies.
The extended warranty is available on EOS-1D Mark IV purchases that are made, or have been made, in specific countries in Europe. The countries where the two-year warranty is available are Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Greece, Germany, Hungary, Ireland, Italy, Iceland, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
To be eligible for the extended warranty customers must provide a valid proof of purchase. For full terms and conditions please click here or download the 'Canon EOS-1D Mark IV Two-Year Warranty: terms & conditions' pdf from the 'Downloads' box on the right hand side of this page. Please note that within the Download pdf terms and conditions are available in all languages relevant to the participating countries, as mentioned above, where the warranty is available.
Information about Canon's standard terms and conditions of warranty will also be found in the two-year warranty leaflet that will be available in each EOS-1D Mark IV DSLR box from mid-April 2011.
It would lead one to believe there was something wrong with early models that warrants a repair. I’ve had some issues with low-light performance, but otherwise mine has been pretty solid.
I have an email out to Canon to get a formal reply to learn more about what is going on here.
I will update this article when I learn more.